Mixing apparatus



Jan. 27, 1942. MILLER 2,270,958

MIXING APPARATUS Filed March 2, 1940 4 Sheets-Sheet l Jan. 27, 1942. WLLER 2,270,958

MIXING APPARATUS Filed March 2, 1940 4 Sheets-Shet 2 7 4 .INVENTOR.

v rMDMZZe? 21)? ATTORNEYS 4 Sheets-Sheet 3 Jan. 27, 1942. F. D. MILLER MIXING APPARATUS Filed March 2, 1940 Jan. 27, 1942. F. D. MILLER 2,270,958

MIXING APPARATUS Filed March 2, 1940 4 Sheets-Sheet 4 Patented Jan. 27, 1942 UNITED STATES PATENT OFFICE MIXING APPARATUS Application March 2, 1940, Serial No. 321,881

4 Claims.

This invention deals with a mixing device. More especially, it relates to a device for the speedy and efficacious mixing of a body of sediment with a body of liquid in which the sediment is immersed.

An object of the invention is the provision of a more simple, satisfactory,and efficient method of mixing such sediment with such liquid.

Another object is the provision of simple, ,efi'icient, and compact apparatus for mixing a body of sediment with a body of liquid in which it is immersed.

Still another object is the provision of mixing apparatus of a light, compact, and portable character.

A further object is the provision of mixing apparatus of such character that it may be readily applied to the original containers in which the sediment and liquid are packed, to perform the mixing operation in these original containers, without the necessity of transferring the sediment and liquid to a special mixing tank or vat.

A still further object of the invention is the provision of improved gearing especially suitable for driving one shaft from another shaft of the mixing apparatus, but capable also of general use in other fields.

To these and other ends the invention resides in certain improvements and combinations of parts, all as will be hereinafter more fully described, the novel features being pointed out in the claims at the end of the specification.

In the drawings:

Fig. 1 is a plan of a mixing device constructed in accordance with a preferred embodiment of the invention; 1

Fig. .2 is a vertical section taken substantially on the line 2-2 of Fig. 1, showing the stirring shaft and stirring blade in their uppermost position in full lines, and in their lowermost position in dotted lines, the container being empty;

Fig. 3 is a horizontal section taken substantially on the line 33 of Fig. 2, showing the parts in one position in which the stirring shaft is free for vertical movement;

Fig. 4 is a view similar to Fig. 3 showing the parts in a diiferent position in which the stirring shaft is locked against downward movement;

Fig. 5 is a View similar to Fig. 2, showingthe container with liquid and sediment therein, and with the stirring blade operating on the top of the body of sediment;

Fig. 6 is a perspective View of a sleeve in which the stirring shaft is mounted; I

Fig.7 is a perspective view of the stirring shaft; 55

(Cl. Z59-103) Fig. 8 is a horizontal section taken substantially on the line 8--8 of Fig. 5;

Fig. 9 is a vertical section taken substantially on the line 99 of Fig. 1, illustrating certain features of the gearing;

Fig. 10 is a side elevation, with parts in vertical section, further illustrating the gearing, and

Fig. 11 is a fragmentary view of the same parts shown in Fig. 10, viewed from a direction at right angles to the direction of Fig. 10.

The same reference numerals throughout the several views indicate the same parts.

It is found that many fluid mixtures upon standing for some length of time, such as in a warehouse or on the shelves of a store, will settle into a layer of sediment in the bottom of the container in which'the mixture is packed, and a layer of liquid above the body of sediment. Before the product is used for its intended purpose, however, the body of sediment must be mixed thoroughly in and throughout the body of liquid. The present invention is directed largely, although not exclusively,'to providing a simple and efficient method and means for effecting this mixture.

One example of such fluid mixtures which form layers of sediment upon standing, is ordinary paint. As is well known, after a can of paint has stood undisturbed for some time, the pigment and other solid ingredients will form a mass or body in the lower part of the can, leaving a low concentration of solids in the liquid remaining above the body of solids. Before the paint is used, however, the solids must be thoroughly mixed with the liquids. This mixing is often a difficult task, because the solids frequently form a dense and tenacious body of sediment which is hard to break up and mix with the liquid.

Paint is herein mentioned merely as a typical example, and is not intended as a limitation of the invention, which is applicable equally well to other materials forming or tending to form sedimentary deposits.

According to the present invention the material is mixed by an improved and novel method which includes the steps of agitating the liquid body above the body of sediment, by force applied thereto at one point above the sediment, and concomitantly stirring up the sediment by force applied at another point, in contact with the sediment. The body of sediment is broken up into small particles by the force applied to it, and as particles are broken away from the main body of sediment, they are picked up and carried away by the currents in the body of liquid which are caused by the application of force to the liquid itself. Preferably the agitating force applied to the body of liquid is applied in such manner (as by means of a rotating screw propeller, for example) as to produce an inclined or oblique current in the body of liquid, offset laterally from the center of gravity of the body of liquid, and extending obliquely downwardly at a substantial inclination to a vertical line. This produces an advantageous swirling action in the liquid which quickly picks up particles of sediment as they are broken off from the main body of sediment. Preferably the stirring of the main body of sediment is accomplished simultaneously over the major part of the top area of the sediment body (as by means of a rotating blade or arm sweeping over the major portion of the top area of the sediment body at each revolution, for example) and preferably the sediment is stirred or broken up progressively in successive layers, beginning at the top and progressing downwardly. This method avoids the immersion of the stirring member deeply into a substantial body of sediment, which would produce excessive drag on the stirring member, likely to require excessive power to move it or possibly'resulting in breakage of the stirring member. As fast as suc' cessive particles are scraped or otherwise broken off of the top of the sediment body by the stirring member, such particles are picked up by I the current or stream of liquid moving under the influence of the agitating force applied to the liquid body, and become thoroughly mixed with and through the liquid.

When this improved method of mixing is employed, it is relatively economical of power consumption, and results in thorough and eflicient mixing action, achieving superior results as compared with many prior mixing methods.

A preferred embodiment of the apparatus for carrying out this mixing method will now be described with reference to the drawings. The mixing apparatus preferably is of compact and portable form, having no container or tank of its own, but being intended to be placed in cooperative relation to the tanks or containers in which the product to be mixed is already packed. This is advantageous, for it avoids the necessity of transferring the product into a special container for mixing purposes, but if desired, it is obvious that the mixing apparatus herein described may be provided with a special tank of its own and may be used permanently in connection with such tank, instead of being transferred from one container to another.

In the form here shown as an illustrative example, the portable mixing device is intended to be applied to a paint can of the usual standard five gallon size, of the usual circular cylindrical shape with its central axis vertical, such a can being indicated at 2| in Figs. 2, 5, and 8 of the drawings. When the contents of the can 2| are to be mixed, the regular cover of the can (not shown) is removed, of course, and over the can is placed a support 23 in the form mainly of a flat plate having a down turned marginal flange 25 loosely surrounding the upper portion of the can 2|. The plate 23 rests upon and is supported by the upper edges of the can 2|, and

may be clamped thereto by any suitable releasable clamping device, such as the clamping screws 21 (Fig. 1) threaded through the flange 25 and bearing against the walls of the can 2|.

The plate 23 preferably has two arcuate observation slots 3| (Figs. 1 and 2) each provided with a closure 33 pivoted near one end at 35 to the plate 23 and cooperating at the other end with a fastening device such as a screw clamp 31. When the clamp 31 is released, the closure 33 may be swung to one side, as shown in dotted lines in Fig. 1, to enable observation of the contents of the can 2|. When observation is completed, the closure may be closed and held tightly in closed position by the clamp 31.

The support 23 is provided with a central opening. Resting on the top of the plate 23 around this opening is a gear box 4| secured to the plate 23 as by means of screws 43. This gear box is provided with upper and lower ball bearings (Fig. 5) in which is journaled a sleeve 41 (Figs. 5 and 6). Surrounding the lower end of the sleeve 41, below the lower ball bearing, is an oil seal 49 so that oil supplied to the bearings will not drip downwardly into the container 2|.

The sleeve 47 has an axial opening therethrough, of any suitable non-circular cross section, preferably square, as shown in Fig. 6. This opening receives a shaft 5| (Figs. 2, 5, and 7) of corresponding non-circular cross section, but having a loose sliding fit in the sleeve so that the shaft may move axially upwardly and downwardly through the sleeve, while remaining at all times non-rotatably connected thereto so that the shaft must rotate whenever the sleeve rotates. This shaft, which may for convenience be called the stirring shaft, is approximately coincident with the vertical central axis of the cylindrical container 2|. A stirring blade 53 is secured to the lower end of the stirring shaft 5|, preferably in a pivotal manner permitting upward and downward tilting of the stirring blade through a limited range, although the stirring blade must rotate with the shaft. For instance, the stirring blade may be provided with an opening therethrough into which the shaft extends, this opening being of such Width in one direction as to embrace the shaft reasonably closely, as shown in Fig. 8. and in the other direction being flared toward top and bottom of the stirring blade, as shown in dotted lines in Figs. 2 and 5, to permit the desired limited range of tilting movement. A pin 55 extends through the stirring blade and through the shaft 5| to secure the blade to the shaft.

The stirring blade itself preferably has two arms symmetrically disposed with respect to the shaft 5|, each arm being approximately radial but having nevertheless a slight backward curvature from the center outwardly toward the free end, with relation to the direction of rotation shown by the arrow in Fig. 8. Each arm preferably has a relatively thin or knife-like forward edge, and a thicker rear or trailing edge. The increase in thickness of the arm, from its forward edge to its trailing edge, is preferably achieved by making the upper surface of the arm inclined upwardly from the forward edge to the trailing edge, the bottom surface of the arm being substantially horizontal, so that a vertical cross section through the arm, taken on a plane at right angles to the length of the arm, would exhibit a substantially triangular shape, with the lower surface horizontal and with the upper surface inclined obliquely upwardly from the forward edge to the trailing edge. Each arm of the stirring blade is also preferably tapered in a longitudinal direction, the rear or trailing edge being thicker near the shaft 5| than at the extreme outer ends of the arms, as seen in Figs. 2 and 5.

The shaft and stirring blade 53 are freely movable upwardly and downwardly by sliding the shaft in the sleeve 41, and in operation, the stirring blade is intended to rest by gravity on the top of the body of sediment in the container 2|, and to rotate in contact with such body of sediment, gradually breaking up or disintegrating the upper layers of the body of sediment and progressively eating its way downwardly through the sediment until the whole body is broken up. Thus the stirring blade is never deeply immersed in the sediment, which would require excessive power to turn the blade and perhaps cause breakage of the parts, but it merely skims over the surface of the sediment, taking in effect a thin slice off of the to of the body of sediment at each revolution. It will be noted from Figs. 2, 5, and 8 that the ends of the arms of the stirring blade extend almost to the walls of the container 2|, so that at each revolution (in fact, at each half revolution, in the preferred arrangement here shown) the stirring blade acts upon almost the entire upper surface area of the sediment body.

A stop pin 59 fixed to the stirring shaft 5| comes in contact with the bottom end of the sleeve 41 when the shaft is elevated and serves as a stop limiting upward movement of the shaft. To hold the shaft releasably in its uppermost position when desired, the shaft is provided at one point in its length with oblique notches 6| cut across the corners of the shaft; as shown in Fig. 7. When the shaft is in its uppermost position, these notches lie just above the top of the sleeve 41, and a latching knob 63, having a square 5 shown in Fig. 4 to the unlatching position shown in Fig. 3, so that the square hole through the latching knob is in alinement with the main body of the shaft, then the shaft may pass freely through the latching knob and may descend under the influence of gravity or under pressure manually applied to an upper knob or handle 65 fixed to the upper end of the shaft. The lowermost position of the shaft (shown in dotted lines in Fig. 2) is determined by contact of the upper knob 65 with the latching knob 63 when the latching knob itself rests upon the top of the sleeve 41.

As above mentioned, there is an agitating action in the liquid above the body of sediment, produced concomitantly with the stirring action of the blade 53. This agitating action is preferably produced by a liquid agitator H of the screw propeller type, fixed to the lower end of an agitator shaft l3 which is offset laterally from the stirring shaft 5| and which preferably is arranged at a substantial angular inclination to a vertical line intersecting this shaft 13. The inclination shown in the drawings as an illustrative embodiment is about 18, but it may be varied within wide limits, good results being obtained with inclinations Within the limits of about 10 to 80 to a vertical line. It is generally preferred to make the inclinations somewhere between the limits of 10 and 45. The rotation of the agitator shaft 13 at an inclination as described, produces a strong current in the liquid which extends obliquely downwardly from the propeller H and impinges upon the upper surface of the body of sediment and then swirls around the container, quickly picking up and carrying along the particles of sediment which have been broken off of the main sedimentary body by the action of the stirring blade 53. The off-center and inclined location of the agitator 1| produces an advantageous swirling action somewhat similar to that described in Craddock Patents 1,719,800, granted July 2, 1929, and Reissue 17,683, granted May 27, 1930.

The gear box 4| is preferably extended upwardly as at 15 (Figs. 2, 5, and 9) at an inclination corresponding to the desired inclination of the agitator shaft 13, and in line with this shaft. as shown. This upward extension 15 supports a motor 11 of any suitable kind, such as a conventional electric motor, of known construction. The armature shaft 19 (Fig. 9) of the motor is preferably coaxial with and directly connected to the agitator shaft 13, as by means of a suit able coupling 8| of known construction. At some distance below the motor, the agitator shaft 13 is further supported by a ball bearing 83 mounted in the gear box 4|, an oil seal 85 being provided below this bearing 83 to prevent leakage of oil from the bearing downwardly into the container 2|.

The stirring shaft 5| is driven from the motor I1 and agitator shaft 13 by special gearing which is particularly adapted to driving these shafts, which is also capable of general use wherever shafts at similar angular relations to each other are to be interconnected.

This special gearing comprises a worm |0| (Figs. 2, 9, 10, and 11) mounted on or formed integrally with the shaft 13, and meshing directly with a spiral gear I03 which is mounted on the sleeve 4'! and non-rotatably connected thereto as by means of the key I05. The teeth of the spiral gear |03 may be arranged at different inclinations depending on the angular relation of the axis of the gear I03 to the axis of the gear |0|, and the same is true of the teeth of the worm H, For angular inclinations of about the magnitude shown, the worm |0| preferably has a duplex screw thread thereon, the pitch of the thread being twice the distance between successive threads in an axial direction. The relationship between the axis of the worm |0| and the axis of the spiral gear I03 is such that a common perpendicular to both axes passes substantially through the point of meshing contact of the gears with each other.

This gearing differs from conventional worm gearing, where two shafts are arranged approximately at right angles to each other, in that the worm drives a spiral gear, rather than a worm gear of the conventional kind. It also differs from conventional spiral gearing in that the spiral gear is driven by a worm, rather than by another spiral gear. It is a combination of worm and spiral gearing which is particularly effective for connecting shafts at an angular relation of this kind, and is capable of general use for driving one shaft from another, where the two shafts are laterally offset with respect to each other and where the angular relation between one shaft and a line intersecting this shaft and parallel to the second shaft is between the limits of about 10 and the pitch of the worm and the spiral gear being varied, of course, for diiferent angular relations.

With this gearing arrangement, the agitator H is driven considerably faster than the stirring blade 53, and in the opposite direction, as seen from the arrows in Fig. 8. It is found that this speed and direction relation is advantageous in quick and efiicient mixing of the sediment with the liquid. A speed ratio which has been found quite satisfactory in use is to drive the agitating shaft 13 at about 1750 revolutions per minute (this being the speed of the electric motor ll directly connected to the agitating shaft) and to drive the mixing shaft 5| at about 90 revolutions per minute, the special gearing giving a speed reduction of about twenty to one.

As above mentioned, the device is preferably of a portable character. To aid in moving it from place to place, it may conveniently be provided with a pair of handles I89 secured to the frame of the motor 71 on opposite sides thereof. When the clamps 21 are released, a straight upward pull on the handles [$9 lifts the entire device off of the container 2| and it may then be applied to another container the contents of which are to be mixed, or-may be laid aside until needed.

In operation, assuming that, for example, a five gallon can or container of paint is to be mixed, the original cover is removed from the can and the mixing device is applied to the open top of the can and clamped thereto by the screws 21. At the time of application the stirring shaft 5| of the device is at its uppermost position, being held in this position by the latching knob 63.

In this uppermost position, the stirring blade 53 is just below the agitating propeller H, as seen in Fig. 2, so as not to hit the propeller during rotation of the blade.

The can, especially if it has stood a long time, is likely to have a body of sediment in the bottom, up to a level such as indicated at H3 in Fig. 5, and above this body of sediment, a body of liquid up to the level indicated at H5. The latching knob 63 is then released so that the stirring shaft 5! and blade 53 may descend until the blade rests on top of the body of sediment, as shown in Fig. 5. The motor is started so that both shafts begin to revolve, the stirring shaft 5| and its blade 53 revolving relatively slowly (such as 90 R. P. M.) and the agitating shaft with its propeller revolving much more rapidly (such as 1750 R. P. M., for example). Due to the flat lower surface and upwardly inclined upper surface of the stirrin blade 53, the blade during rotation will tend to dig slightly into the surface of the sediment I it, but not to such an excessive extent as to imbed the blade deeply in the sediment or cause stalling of the motor. Each revolution of the stirring blade will scrape off or dislodge a small surface layer over substantially the entire top area of the sediment, this action progressing downwardly as successive portions of the sediment body are broken away, the blade 53 and shaft 5| meanwhile descending by gravity as fast as permitted by the disintegration of the sediment body. As the particles of sediment are disintegrated, they are immediately picked up, carried away, and thoroughly mixed through the body of liquid because of the strong current produced by the rapidly rotating agitator II, this current impinging downwardly and obliquely on the top of the sediment body and then swirling around the container, as already mentioned. The agitator II and the strong current produced thereby continue and complete the disintegrating action initiated by the blade 53, as well as the mixing action. By the time the stirring blade 53 reaches the bottom of the container and disintegrates the last of the sedimentary body, the sediment is thoroughly mixed in and throughout the liquid, and the operation can be discontinued.

If the top of the body of sediment is initially uneven or'inclined, due for example to having stored the can or container in a position slightly inclined from the vertical, the stirring blade 53 can readily accommodate itself to the inclined surface of the sediment, by reason of the pivotal connection and limited range of tilting movement of the blade with relation to its shaft, and thus excessive digging of the blade into the sedimentary body on the high side of the body is avoided.

Such pivoting of the stirring blade also enables it to deflect and move over or under a dent which may be encountered in the side wall of the container, so as to avoid obstruction of its movement. The backward curvature of each arm of the stirring blade, from the center toward its free end, serves to push the separated sediment toward the walls of the container and to there mash and disintegrate any lumps until small enough to be picked up by the circulating currents produced by the agitator l I The device is exceedingly compact and efiicient, and requires low power consumption, a motor of one-quarter horse power being ordinarily sufficient for operations on a five gallon can of ordinary paint. Also the device is extremely free from vibration and noise, which are noticeable defects of many prior mixing devices.

While one embodiment of the invention has been disclosed, it is to be understood that the inventive idea may be carried out in a number of ways. This application is therefore not to be limited to the precise details described, but is intended to cover all variations and modifications thereof falling within the scope of the appended claims.

I claim:

1. A portable self-contained motor-driven paint mixer including a cover member to be placed across and supported by the top edge of an open paint can to serve as a cover for said can to prevent splashing of the paint out of the can during mixing, an electric motor mounted on and supported by said cover with the axis of said motor laterally offset from the center of said cover and inclined at an acute angle to a vertical line, a propeller shaft arranged substantially in alinement with said motor axis and driven thereby, a propeller agitator mounted adjacent the lower end of said shaft to be revolved thereby in a position substantially above the bottom of the paint can to which said mixer is applied, a gear on said propeller shaft approximately at the elevation of said cover, a second gear mounted on said cover for rotation about a substantially vertical axis arranged substantially centrally of said cover, said second gear being in meshing relation to and being driven by said first mentioned gear at a speed of rotation substantially slower than that of said first mentioned gear, a stirring shaft arranged substantially vertically and passing centrally through said second gear in non-rotatable and axially movable relation thereto, a stirring blade mounted on said stirring shaft substantially at the lower end thereof, for contact with sediment in the paint can to break up said sediment by rotation of the blade, and stop means limiting movement of said stirring shaft in an upward direction to a position in which said blade is below the level of said propeller agitator, so that when said stirring shaft is in its uppermost position, said blade will be at an elevation below said propeller agitator and can rotate freely without striking said propeller agitator.

2!. A construction as described in claim 1, in which said stirring blade includes an arm extending laterally from said stirring shaft, the cross section of said arm being of generally triangular shape with its bottom edge extending approximately horizontally and with its upper edge extending obliquely upwardly from a relatively thin leading edge to a materially thicker trailing edge. i

3. A portable paint mixer including a cover member to be applied to and supported by the upper edge of an open paint can, a gear mounted on said cover member for rotation about a substantially vertical axis arranged substantially centrally of said cover member, means for rotating said gear, a stirring shaft arranged substantially vertically and passing centrally through said gear in non-rotatable and axially movable relation thereto, and a stirring blade mounted on said shaft adjacent the lower end thereof, said stirring blade having an inclined upper surface acting as a plow during rotation of said shaft and blade to loosen and remove a thin layer of paint sediment on which said blade is resting, and having a substantially flat horizontal bottom surface of substantial area to form a bearing on said paint sediment to prevent said blade, during rotation, from descending too rapidly and digging too quickly into said paint sediment.

4. A portable self-contained motor driven paint mixer including a support member to be placed across and supported by the top edge of an open paint can,an electric motor fixed to and supported by said support member, a stirring shaft and an agitating shaft both mounted on said support member, said stirring shaft being arranged substantially vertically substantially at the center of the paint can to which said mixer is applied, said agitating shaft having its axis lying substantially in a vertical plane materially offsetlaterally from said stirring shaft and having its axis materially inclined to a vertical line in such plane, means for driving both of said shafts from said motor, said driving means being arranged to drive said agitating shaft at a substantially faster rate than said stirring shaft, a stirring blade mounted on said stirring shaft substantially at the lower end thereof and extending laterally thereof, said blade being movably connected to said shaft for limited upward and downward tilting movement relative thereto while turning therewith, said stirring shaft being mounted for upward and downward movement relative tosaid supporting member so that said stirring blade may sweep over the top surface of sediment in the paint can and disintegrate a surface layer of said sediment and may move downwardly progressively as the sediment is progressively disintegrated, and a propeller agitator mounted substantially at the lower end of said agitating shaft in a position substantially above the bottom of the paint can to which said mixer is applied, to rotate initially in the liquid above the body of said sediment and to create currents in said liquid to pick up and carry along the particles of sediment disintegrated by movement of said stirring blade.

FRANK D. MILLER. 

